System and method for a three-piece design of a magnetic head assembly

ABSTRACT

A system and method for an improved magnetic head arm assembly (HAA) is disclosed. The HAA includes three principal components, a head gimbal assembly (HGA), a flexible printed circuit (FPC) assembly, and an actuator coil assembly. The design allows for HAA rigidity, yet each of the components is designable and manufacturable independent of one another, in addition to other advantages over current methods.

BACKGROUND INFORMATION

[0001] The present invention relates to magnetic hard disk drives. Morespecifically, the present invention relates to a system for an improvedmagnetic head arm assembly (HAA).

[0002] Among the better known data storage devices are magnetic diskdrives of the type in which a magnetic head slider assembly floats on anair bearing at the surface of a rotating magnetic disk. Such disk drivesare often called ‘Winchester’-type drives. In these, one or more rigidmagnetic disks are located within a sealed chamber together with one ormore magnetic head slider assemblies. The magnetic disk drive mayinclude one or more rigid magnetic disks, and the slider assemblies maybe positioned at one or both sides of the magnetic disks.

[0003] Typically, each magnetic head slider assembly in magnetic diskdrives of the type referred to is coupled to the outer end of an arm orload beam. FIG. 1 provides a top view of a typical magnetic head arm(HAA) base plate. The slider assembly 102 is mounted in a manner whichpermits gimbaled movement at the free outer end of the arm 106 such thatan air bearing between the slider assembly 102 and the surface of themagnetic disk can be established and maintained. The elongated arm iscoupled to an appropriate mechanism, such as a voice-coil motor (VCM)104, for moving the arm 106 across the surface of the disk so that amagnetic head contained within the slider assembly 102 can addressspecific concentric data tracks on the disk for writing information onto or reading information from the data tracks.

[0004] An example of an HAA 108 having a gimbaled mount for a magnetichead slider assembly 102 is provided by U.S. Pat. No. 3,931,641 ofWatrous. The HAA 108 described in the Watrous patent includes arelatively rigid load beam (arm) 106 having a rigid bearing member at afree outer end thereof for receiving a protuberance on a spring element.The spring element is spot welded to the load beam and has an endthereof defining a flexure. The flexure includes a pair of stiffcrosslegs mounted on an opposite pair of flexible outer fingers and acentral finger. The central finger mounts a magnetic head sliderassembly, and gimbaled movement is provided by the load protuberance onthe spring element that is held in contact with the bearing member atthe end of the rigid load beam. Such arrangements provide desiredgimballing action by allowing pitch and roll of the slider assemblyaround mutually orthogonal axes while resisting radial, circumferential,and yaw motions. Other patents, such as U.S. Pat. No. 3,931,641, No.4,620,251, No. 4,796,122, and No. 5,313,353, describe other HAA designs.

[0005]FIG. 1 is representative of these designs, which are typical inthe art. The slider 102 is potted to the HAA suspension and the headgimbal assembly (HGA) 110. The HGA 110 connects to the arm 106 through aball stacking process (See FIG. 2). A flexible printed circuit (FPC) isbonded to the arm 106 by solder. Further, a rotational bearing 114 isscrewed to an arm bearing hole, and the voice coil motor (VCM) 104 isglued to the arm 106 by epoxy.

[0006]FIG. 2 illustrates a typical process of ball stacking for thepurpose of securing the HGA 210 to the arm 206 and the problem of stressand warpage due to said process. As seen in FIG. 2a, to secure the HGA210 to the arm 206, the HGA 210 is located such that a raised portion212 of the ball stacking assembly (of the HGA 210) is inserted into anopening 214 in the arm 206. A swag ball 216 is inserted into aball-stacking hole 218 (See 118, FIG. 1). Then the swag ball 216 isforced 220 downward into the ball-stacking hole 218. Because the middlediameter of the ball-stacking hole 218 is less than that of the swagball 216, the walls of the raised portion 212 are expanded as the swagball 216 enters. This expansion causes forced contact between the outerwalls of the raised portion 212 and the inner walls of the opening 214,securing the HGA 210 to the arm 206.

[0007] Although ball stacking works well to secure the HGA 210 to thearm 206, the deformations to the HGA 210 and arm 206 adversely affectthe gram load of the HGA. FIG. 2b illustrates the deformation andresidual stress experienced by the HGA 210 and the arm 206.

[0008] Many problems exist with the described designs typical in theart. In addition to the problem of the gram load change occurring afterball stacking, a problem is suspension/arm/coil motion independence.Motion tolerance between the components is often too great because ofplay involved in the securing means between the components.

[0009] Because of the strict dimensional parameters needed forimplementation of ball-stacking, improper (too large) tolerance may leadto one or more negative consequences. For example, HGA 210 and arm 206may be seriously deformed leaving a great amount of residual stress. Asa result, the load-gram pitch/roll performance of HGA 210 afterball-stacking may become fairly poor. As another negative consequence,with even a small amount of deformation and residual stress, theassembly is more likely to come apart under usage, reducing reliability.

[0010] Further, if the HGA 210 is secured to arm 206 by ball stacking,it is possible that a large amount of torque would be necessary forcomponent separation. A large amount of torque could damage thecomponents. By contrast, if the torque requirement is too low, thedevice may come apart when not desired, such as during operation.

[0011] Because of the motion independence and HGA/arm deformation due toball stacking, correct head alignment is difficult. Further, the typicalmethod of design and manufacture for such HAA's is complicated andexpensive, and the re-work process is difficult as well.

[0012] It is therefore desirable to have a system and method for animproved magnetic head arm assembly (HAA) that avoids theabove-mentioned problems, in addition to other advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 provides a top view of a typical magnetic head armassembly.

[0014]FIG. 2 illustrates a typical process of ball stacking for thepurpose of securing the HGA to the arm and the problem of stress andwarpage due to said process.

[0015]FIGS. 3a-d provide a illustrations of the components of athree-piece magnetic head and their assembly according to principles ofthe present invention.

[0016]FIGS. 4a-e provides an illustration of the components of auniversal (unimount) HGA assembly and their assembly according toprinciples of the present invention.

[0017]FIG. 5 provides an illustration of the components of an FPCassembly according to principles of the present invention.

[0018]FIG. 6 provides an illustration of the components of an actuatorcoil assembly according to principles of the present invention.

[0019]FIG. 7 illustrates methods for securing the FPC assembly to theactuator coil assembly.

[0020]FIG. 8 illustrates methods for securing the unimount HGA assemblyto the actuator coil assembly.

DETAILED DESCRIPTION

[0021]FIGS. 3a-d provide a illustrations of the components of athree-piece magnetic head and their assembly according to principles ofthe present invention. In an embodiment, the first of three pieces is aunimount head gimbal assembly (HGA) 302; the second piece is a flexibleprinted circuit (FPC) assembly 304; and the third piece is an actuatorcoil assembly 306.

[0022] In an embodiment, the FPC assembly 304 is secured to the actuatorcoil assembly 306. For this securement, a part of the FPC (the FPCmating portion) 314 is attached to the actuator body 310 at an actuatormating portion (second actuator mating portion) 318 by rivetdeformation. Adhesive bonding and solder bonding are each alternativeembodiments. Also for this securement, in an embodiment, a coil 312 isattached to an FPC trace by solder bonding. Stitch bonding is also analternative embodiment. (See FIG. 7). In an embodiment, the interfacesurfaces of the mating portions 314,318 are flat and smooth to aidbonding with materials such as adhesive, solder, etc. Further, havingflat, smooth mating surfaces of non-complex contours simplifies theprocess of designing and manufacturing each of the components of thethree-piece magnetic head assembly independently of each other. As longas the mating portions match up, the components can be coupled together.

[0023] In an embodiment, the unimount HGA assembly 302 is secured at anHGA mating portion 320 to a first mating portion 322 of the actuatorcoil assembly 306. In one embodiment, this is done by adhesive bonding.Rivet deformation and screw mounting bonding are each alternativeembodiments. (See FIG. 8). As above, in an embodiment, the interfacesurfaces of the mating portions 320,322 are flat and smooth to aidbonding with materials such as adhesive, solder, etc. Further, havingflat, smooth mating surfaces of non-complex contours simplifies theprocess of designing and manufacturing each of the components of thethree-piece magnetic head assembly independently of each other. Asstated, as long as the mating portions match up, the components can becoupled. Accordingly, mating portions 314, 318, 320, and 322 can bereferred to as “universal” in that they are designed to interface with avariety of differently designed and manufactured components.

[0024] In an embodiment, the unimount HGA assembly 302 is secured to theFPC assembly 304. For this securement, in an embodiment, aflex-suspension assembly (FSA) 316 is attached to an FPC bonding pad 318by tape automated bonding (TAB). Anisotropic conductive film (ACF)bonding is envisioned for an alternative embodiment.

[0025]FIGS. 4a-e provides an illustration of the components of auniversal (unimount) HGA assembly and their assembly according toprinciples of the present invention. In an embodiment, the firstcomponent is a unimount baseplate 402. Second, in an embodiment, is amulti-piece loadbeam 404. Third, in an embodiment, is an FSA trace 416.And fourth, in an embodiment, is a slider 406.

[0026] In an embodiment, the multi-piece loadbeam 404 is secured to theunimount baseplate 402 by laser welding. Also, in an embodiment, the FSAtrace 416 is secured to the HGA assembly (unimount baseplate 402 and themulti-piece loadbeam 404) by ultra-violet (UV) epoxy bonding. Utilizingthese methods of securement prevents the residual stress and deformationproblems of ball stacking (swaging). The slider 406 is attached to theassembly, thereafter.

[0027]FIG. 5 provides an illustration of the components of an FPCassembly according to principles of the present invention. In anembodiment, a metal bracket 502 is attached to one end of the FPC 508 bylamination. In an embodiment, a plastic bracket 504 is attached to theopposite end of the FPC 508 by pin 510 insertion.

[0028]FIG. 6 provides an illustration of the components of an actuatorcoil assembly according to principles of the present invention. In anembodiment, the coil 612 is attached to the actuator body 610 by epoxy614.

[0029]FIG. 7 illustrates methods for securing the FPC assembly 304 tothe actuator coil assembly 706. As stated, in an embodiment, the FPC 708is attached to the actuator body 710 by rivet 730 deformation. Asstated, in an embodiment, the coil 712 is attached to the FPC 708 bysolder 732 bonding.

[0030]FIG. 8 illustrates methods for securing the unimount HGA assembly802 to the actuator coil assembly 806. In one embodiment, this is doneby ultra-violet (UV) epoxy 830. In another embodiment, this is done byrivet 832 deformation. In another embodiment, this is done by screw 834mounting.

[0031] Although several embodiments are specifically illustrated anddescribed herein, it will be appreciated that modifications andvariations of the present invention are covered by the above teachingsand within the purview of the appended claims without departing from thespirit and intended scope of the invention.

1-9. (Cancelled)
 10. A method for manufacturing a magnetic head armassembly (HAA) comprising: providing a head gimbal assembly (HGA), saidHGA having an HGA mating portion; providing a flexible printed circuit(FPC) assembly, said FPC having an FPC mating portion; providing anactuator coil assembly, said actuator coil assembly having a firstmating portion and a second mating portion, wherein each of said HGA,FPC assembly, and actuator coil assembly is manufactured independentlyfrom each other; coupling said HGA mating portion to said actuator coilassembly first mating portion; and coupling said FPC mating portion tosaid actuator coil assembly second mating portion.
 11. The method ofclaim 10, wherein said actuator coil assembly first mating portion andsecond mating portion each have substantially smooth interface surfaces,and wherein said HGA mating portion and FPC mating portion each havesubstantially smooth interface surfaces.
 12. The method of claim 11,wherein said actuator coil assembly first mating portion and secondmating portion each have substantially flat interface surfaces, andwherein said HGA mating portion and FPC mating portion each havesubstantially flat interface surfaces.
 13. The method of claim 12,wherein said actuator coil assembly first mating portion is recessed andcontoured to interface said HGA mating portion and wherein said actuatorcoil assembly second mating portion is contoured to interface said FPCmating portion.
 14. The method of claim 12, wherein at least one of saidHGA, said FPC assembly, and said actuator coil assembly is manufacturedby injection molding.
 15. The method of claim 14, wherein said HGA is aunimount HGA.
 16. The method of claim 15, wherein said unimount HGAincludes a unimount baseplate containing said HGA mating portion, amulti-piece loadbeam, a flex-suspension assembly (FSA) trace, and aslider device.
 17. The method of claim 16, wherein said FPC assemblyincludes a plastic bracket, a metal bracket containing said FPC matingportion, and a flexible printed circuit.
 18. The method of claim 17,wherein said actuator coil assembly includes a coil and an actuator bodycontaining said first and second mating portions.
 19. The method ofclaim 18, wherein said FPC is coupled to said actuator body by rivetdeformation.
 20. The method of claim 18, wherein said FPC is coupled tosaid actuator body by adhesive bonding.
 21. The method of claim 18,wherein said FPC is coupled to said actuator body by solder bonding. 22.The method of claim 18, wherein said coil is coupled to an FPC trace bysolder bonding.
 23. The method of claim 18, wherein said coil is coupledto an FPC trace by stitch bonding.
 24. The method of claim 18, whereinsaid HGA assembly is coupled to said FPC assembly by adhesive bonding.25. The method of claim 18, wherein said HGA assembly is coupled to saidFPC assembly by rivet deformation.
 26. The method of claim 18, whereinsaid HGA assembly is coupled to said FPC assembly by screw mounting. 27.The method of claim 18, wherein said FSA trace is coupled to a bondingpad of said FPC assembly by tape automated bonding (TAB).
 28. The methodof claim 18, wherein said FSA trace is coupled to a bonding pad of saidFPC assembly by anisotropic conductive film (ACF) bonding.
 29. Themethod of claim 18, wherein said multi-piece loadbeam is coupled to saidunimount baseplate by laser welding.
 30. The method of claim 18, whereinsaid FSA trace is coupled to said HGA assembly by ultra-violet (UV)epoxy bonding.
 31. The method of claim 18, wherein said FPC assembly iscoupled to said metal bracket by lamination.
 32. The method of claim 18,wherein said FPC assembly is coupled to said plastic bracket by pininsertion.
 33. The method of claim 18, wherein said coil is coupled tosaid actuator body by epoxy.